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🔗 Physics 🔗 Measurement

In particle physics and physical cosmology, Planck units are a system of units of measurement defined exclusively in terms of four universal physical constants: c, G, ħ, and k_B. Expressing one of these physical constants in terms of Planck units yields a numerical value of 1. They are a system of natural units, defined using fundamental properties of nature (specifically, properties of free space) rather than properties of a chosen prototype object. Originally proposed in 1899 by German physicist Max Planck, they are relevant in research on unified theories such as quantum gravity.

The term Planck scale refers to quantities of space, time, energy and other units that are similar in magnitude to corresponding Planck units. This region may be characterized by particle energies of around 10¹⁹ GeV or 10⁹ J, time intervals of around 10⁻⁴³ s and lengths of around 10⁻³⁵ m (approximately the energy-equivalent of the Planck mass, the Planck time and the Planck length, respectively). At the Planck scale, the predictions of the Standard Model, quantum field theory and general relativity are not expected to apply, and quantum effects of gravity are expected to dominate. One example is represented by the conditions in the first 10⁻⁴³ seconds of our universe after the Big Bang, approximately 13.8 billion years ago.

The four universal constants that, by definition, have a numerical value 1 when expressed in these units are:

• c, the speed of light in vacuum,
• G, the gravitational constant,
• ħ, the reduced Planck constant, and
• k_B, the Boltzmann constant.

Variants of the basic idea of Planck units exist, such as alternate choices of normalization that give other numerical values to one or more of the four constants above.

🔗 Human rights 🔗 Italy 🔗 Philosophy 🔗 Politics 🔗 Philosophy/Social and political philosophy 🔗 Sociology 🔗 Discrimination 🔗 LGBTQ+ studies

“Ur-Fascism” or “Eternal Fascism: Fourteen Ways of Looking at a Blackshirt” (in Italian: Il fascismo eterno, or Ur-Fascismo) is a renowned essay authored by the Italian philosopher, novelist, and semiotician Umberto Eco. First published in 1995, this influential essay provides an analysis of fascism, a definition of fascism, and discusses the fundamental characteristics and traits of fascism. Drawing on Eco's personal experiences growing up in Mussolini's Italy and his extensive research on fascist movements, the essay offers his insights into the nature of fascism and its manifestations.

🔗 Law 🔗 Royalty and Nobility

Lèse-majesté ( or ;), a French term meaning "to do wrong to majesty", is an offence against the dignity of a reigning sovereign or against a state.

This behaviour was first classified as a criminal offence against the dignity of the Roman Republic of ancient Rome. In the Dominate, or Late Empire period, the emperors eliminated the Republican trappings of their predecessors and began to identify the state with their person. Although legally the princeps civitatis (his official title, meaning, roughly, 'first citizen') could never become a sovereign because the republic was never officially abolished, emperors were deified as divus, first posthumously but by the Dominate period while reigning. Deified emperors enjoyed the same legal protection that was accorded to the divinities of the state cult; by the time it was replaced by Christianity, what was in all but name a monarchical tradition had already become well-established.

Narrower conceptions of offences against Majesty as offences against the crown predominated in the European kingdoms that emerged in the early medieval period. In feudal Europe, some crimes were classified as lèse-majesté even if they were not intentionally directed against the crown. An example is counterfeiting, so classified because coins bore the monarch's effigy and/or coat of arms.

With the disappearance of absolute monarchy in Europe (with exception of Vatican City), lèse-majesté came to be viewed as less of a crime. However, certain malicious acts that would have once been classified as the crime of lèse-majesté could still be prosecuted as treason. Future republics that emerged as great powers generally still classified as a crime any offence against the highest representatives of the state. These laws are still applied as well in monarchies outside of Europe, such as modern Thailand and Cambodia.

🔗 Physics

A nanoscale vacuum-channel transistor (NVCT) is a theoretically visioned transistor in which the electron transport medium is a vacuum. In a traditional solid-state transistor, a semiconductor channel exists between the source and the drain, and the current flows through the semiconductor. However, in a nanoscale vacuum-channel transistor, no material exists between the source and the drain, and therefore, the current flows through the vacuum. However, experimental realization of such a transistor has not been demonstrated.

Theoretically, a vacuum-channel transistor is expected to operate faster than a traditional solid-state transistor, and have higher power output. Moreover, vacuum-channel transistors are expected to operate at higher temperature and radiation level than a traditional transistor making them suitable for space application.

The development of vacuum-channel transistors is still at a very early research stage, and there are only limited study in recent literature such as vertical field-emitter vacuum-channel transistor, gate-insulated planar electrodes vacuum-channel transistor, vertical vacuum-channel transistor, and all-around gate vacuum-channel transistor.

🔗 Computing 🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Poland 🔗 Computing/Early computers

The bomba, or bomba kryptologiczna (Polish for "bomb" or "cryptologic bomb"), was a special-purpose machine designed around October 1938 by Polish Cipher Bureau cryptologist Marian Rejewski to break German Enigma-machine ciphers.

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🔗 Electrical engineering

The sulfur lamp (also sulphur lamp) is a highly efficient full-spectrum electrodeless lighting system whose light is generated by sulfur plasma that has been excited by microwave radiation. They are a particular type of plasma lamp, and one of the most modern. The technology was developed in the early 1990s, but, although it appeared initially to be very promising, sulfur lighting was a commercial failure by the late 1990s. Since 2005, lamps are again being manufactured for commercial use.

🔗 Mathematics

In linear algebra, the singular value decomposition (SVD) is a factorization of a real or complex matrix that generalizes the eigendecomposition of a square normal matrix to any ${\displaystyle m\times n}$ matrix via an extension of the polar decomposition.

Specifically, the singular value decomposition of an ${\displaystyle m\times n}$ real or complex matrix ${\displaystyle \mathbf {M} }$ is a factorization of the form ${\displaystyle \mathbf {U\Sigma V^{*}} }$, where ${\displaystyle \mathbf {U} }$ is an ${\displaystyle m\times m}$ real or complex unitary matrix, ${\displaystyle \mathbf {\Sigma } }$ is an ${\displaystyle m\times n}$ rectangular diagonal matrix with non-negative real numbers on the diagonal, and ${\displaystyle \mathbf {V} }$ is an ${\displaystyle n\times n}$ real or complex unitary matrix. If ${\displaystyle \mathbf {M} }$ is real, ${\displaystyle \mathbf {U} }$ and ${\displaystyle \mathbf {V} =\mathbf {V^{*}} }$ are real orthonormal matrices.

The diagonal entries ${\displaystyle \sigma _{i}=\Sigma _{ii}}$ of ${\displaystyle \mathbf {\Sigma } }$ are known as the singular values of ${\displaystyle \mathbf {M} }$. The number of non-zero singular values is equal to the rank of ${\displaystyle \mathbf {M} }$. The columns of ${\displaystyle \mathbf {U} }$ and the columns of ${\displaystyle \mathbf {V} }$ are called the left-singular vectors and right-singular vectors of ${\displaystyle \mathbf {M} }$, respectively.

The SVD is not unique. It is always possible to choose the decomposition so that the singular values ${\displaystyle \Sigma _{ii}}$are in descending order. In this case, Σ (but not always U and V) is uniquely determined by M.

The term sometimes refers to the compact SVD, a similar decomposition ${\displaystyle \mathbf {M} =\mathbf {U\Sigma V^{*}} }$ in which Σ is square diagonal of size ${\displaystyle r\times r}$, where ${\displaystyle r\leq \min\{m,n\}}$ is the rank of M, and has only the non-zero singular values. In this variant, ${\displaystyle \mathbf {U} }$ is an ${\displaystyle m\times r}$ matrix and ${\displaystyle \mathbf {V} }$ is an ${\displaystyle n\times r}$ matrix, such that ${\displaystyle \mathbf {U^{*}U} =\mathbf {V^{*}V} =\mathbf {I} _{r\times r}}$.

Mathematical applications of the SVD include computing the pseudoinverse, matrix approximation, and determining the rank, range, and null space of a matrix. The SVD is also extremely useful in all areas of science, engineering, and statistics, such as signal processing, least squares fitting of data, and process control.

🔗 Internet 🔗 Computing

.test is a reserved top-level domain intended for usage in software testing. It is guaranteed to never be registered into the Internet.

Along with .test, there are 11 other reserved test domains: .测试, .परीक्षा, .испытание, .테스트, .טעסט, .測試, .آزمایشی, .பரிட்சை, .δοκιμή, .إختبار, and .テスト.